1. Field of the Invention
This invention relates to a circuit arrangement for an uninterrupted power supply, and more particularly to an intelligent detection and control device capable of detecting incoming AC power and supplying a more stable regulated power when the incoming AC power fails or is abnormal.
2. Description of the Prior Art
The domestic electrical power system is AC110V in Taiwan. Another rated voltage is possible in other foreign electrical power system. It is a common problem that the line voltage of the electrical power system is changed by the electrical load effect. For example, it has been found that the incoming voltage from the power company in the daytime is always lower than that in the nighttime. The major reason is that a heavier power consumption is required in the daytime. In addition, a load disturbance problem may be present on the power transmission line. In such poor conditions, it is difficult to supply stable power to electrical devices, particularly to an electrical appliance requiring a pure and stable power source.
The conventional uninterrupted power supply (abbreviated UPS) is widely used in electrical devices, such as computer or test instruments, but it is merely a simple backup power source which switches from the power supplied by the power company to a backup battery set when the power fails. Furthermore, the present invention has been filed in Taiwan under the application Serial number of 83202739, the other corresponding applications are 94205201.3 (China), 08/327.935 U.S.A.), DE(G 9407011.3).